1. Field of the Invention
This invention relates to bicycles possessing a propulsion system composed of lever machines.
2. Description of the Related Art
In the bicycle industry there are a multitude of pedal propulsion systems that offer a wide variety of commuting benefits for the bicyclist. Notably, these are pedaling systems that provide multi-speed human powered propulsion that allows the rider to pedal with little effort up an incline and increase in speed efficiently.
Currently, the prevalent configuration of bicycles in the market place have a rotary pedaling system that utilizes two pedals, pivotally connected to a rigid assembly of two crank arms and a crank sprocket. Furthermore, these two crank arms mounted to a crank sprocket engage a transmission chain for engaging the rear sprocket of the rear wheel. These pedaling systems vary from multi-speed to single speed, but their mechanical nature restricts their frame design to century old principle structures; which is the need for a bicycle frame to suspend the crank shaft between the front and rear wheels. Furthermore, although these rotary systems utilize crank sprockets in the form of the wheel and axle machine, they cannot have more mechanical advantage than the lever machine, because the fulcrum or shaft of the crank arms is usually positioned close to the level of the axles belonging to the bicycles wheels providing transport. This level restricts the length of the crank arms which acts as levers on the wheel and axle because of its proximity to the ground. However, a lever machine usually amplifies the spreading of propulsion effort along a longer distance and has movements concentrated to pivotal swings instead of a one direction rotational path. Thus, being significantly free from the vertical restrictions of the ground and the riders' range of motion. Because, this effort to move a transport load is spread over a much longer distance using a lever arm than the crank arm, a rider pedaling with levers will have lesser effort pedaling a bicycle.
There have been a myriad of bicycle inventions exploiting the mechanical advantage of the lever machine. U.S. Pat. No. 4,666,173 to Graham (1987) discloses a bicycle having a lever configured pedaling system, with fulcrums positioned behind the rear wheel axle and lever arms extending between the bicycle's wheels providing transport. However, the illustrated lever arms cannot possibly provide sound pedaling efficiency as discovered by my observation of similar lever arms built and applied to a two wheeled vehicle frame. My experimentation with such levers having a pivotal pedal that extended out horizontally from the frontal outer wall of each lever yielded evidence of the right lever twisting clockwise when applying downward force on its pedal and the left lever twisting counter clockwise when applying downward force on its pedal. Looking at the shape of the levers as illustrated in the (U.S. Pat. No. 4,666,173) (FIG. 3), the levers 48 and 50 have the potential for twisting in a like manner, like the similar levers conducted in my experiment. The invention also utilizes an indirect transmission means from the lever to the sprocket of the rear wheel; however, the lever enhanced pedaling system (L.E.P.S.) uses a direct transmission means from its levers to the sprockets of the rear wheel. As illustrated in U.S. Pat. No. 4,666,173 the first transmission means from the lever is a shaft arm and ratchet for moving the pedal sprocket above the rear wheel in one direction. The second transmission means is a chain connected to the pedal sprocket to the rear wheel sprocket. The lever enhanced pedaling system (L.E.P.S.) skips over the extra weight of an indirect transmission means allowing designers using this system to produce a more aero dynamic, less bulky and more efficient bicycle.
Two inventions utilizing the advantages of the lever machine is U.S. Pat. No. 4,666,174 to Efros (1987) and U.S. Pat. No. 5,335,927 to Islas (1994). These inventions are composed of a bicycle having a lever configured pedaling system, with fulcrums positioned in front of the rear wheel axle providing lever ends with the ability to pivot below the bicycles mid-frame portion. These lever pedaling systems have lesser mechanical advantage than the lever enhanced pedaling system (L.E.P.S.), because their levers are shorter in length and thus the effort needed to propel the rider is spread out in a shorter distance from the applied force of the riders'foot to the fulcrum. The lever enhanced pedaling system has a principle configuration which allows the fulcrums to be behind the axle of the rear wheel while its levers are extended from that pivotal area to the area between the vehicle's two wheels. Thus, its lever machines are longer in length than the lever machines in U.S. Pat. Nos. 4,666,174 and 5,335,927 which give the lever enhance pedaling system a greater mechanical advantage.
As mentioned before, the current standard mechanical configuration of bicycles, which has been around since the 19th century, restricts their frame design to having a bicycle frame that suspends the crank shaft between the front and rear wheels. This frame design is usually triangular and tubular, like the U.S. Pat. No. 5,405,157 to Bezerra (1995). The fulcrum of the lever machines in this patent application is suspended by the frame of the bicycle between the front and rear wheels. U.S. Pat. No. 4,857,035 to Anderson (1989) also has a triangular tubular structure and besides it having a lesser mechanical advantage than the L.E.P.S., because its' lever is shorter in length; much of its complex mechanical configuration is exposed, allowing its mechanical components to diminish the beauty of the frames form. The mechanical configuration of the L.E.P.S. allows for a frame structure that conceals much of its' mechanical interactions between its' levers, transmission chains and rear wheel sprockets, thus adding more stream line appeal to the bicycle as well as marketability.